Vapor density measuring apparatus



March 20, 1962 J, H. ROBERTSON VAPOR DENSITY MEASURING APPARATUS Fil edNov. 13, 9

INVENTOR JUDSQN H. ROBERTSON ar/(M0 2, fwa m, 934% ATTORNEY'J7 FIG. 4..

" 3,026,187 Ice Patented Mar. 20, 1962 3,026 187 VAPOR DENSITYNIEXSURING APPARATUS Judson H. Robertson, Knoxville, Tenn., assignor toThe University of Tennessee Research Corporation, Knoxville, Tenn., acorporation of Tennessee Filed Nov. 13, 1959, Ser. No. 852,653 Claims.(Cl. 23292) This invention relates to vapor density measuring apparatusand more particularly to such apparatus in which the sample to bemeasured is vaporized and the air displaced by the vaporization thereofmeasured in the manner proposed by Victor Meyer to determine the vapordensity of the sample.

In the Well-known Victor Meyer method of determining vapor density, aweighed sample of the liquid to be measured is vaporized and the volumeof air displaced from the vaporization unit is measured under theprevailing conditions of temperature and pressure in the room todetermine the vapor density of the sample. If vapor from the samplepasses from the vaporizing apparatus or condenses therein themeasurements are vitiated. The vaporization unit proposed by VictorMeyer in its usual form is made quite long to prevent such condensationor loss of vapor and is therefore rather cumbersome. Even withconventional forms of apparatus vapor can be lost from the vaporizingunit and condensed with the displaced air to thus produce errors in thevapor density determination.

Various modifications have been suggested of the Victor Meyer apparatusto obtain compactness and to eliminate vapor condensation but thesemodifications have undesirable features. In one such modification thedistance the vapor travels before leaving the vaporizing unit isincreased by sealing a J-shaped delivery tube through the bottom of thevaporization bulb with the short end of the tube extending almost to thetop of the vaporization bulb, the long end of the tube extending upthrough the outer heating jacket. The volume of the vaporization bulb inthis apparatus is largely dead space and the vapors must be swept outbetween successive uses of the apparatus. The long leverage of the exitend of the tube makes the tube very susceptible to breakage of thebottom seal when assembly or disassembling the apparatus.

In another modification of the Victor Meyer apparatus a tube is employedin the vaporizer through which the sample is introduced. This tubeprojects downward through a series of bulbs forming annular spaces alongthe seals between the bulbs. The escaping vapor or air expandssuccessively through the small spaces giving a steady flow of air intothe measuring buret. Escape of vapor is minimized by the large capacityof the bulbs. This apparatus is particularly adapted for the study ofmolecular weight of petroleum constituents by the method of limitingdensity but is not advantageously used for regular vapor densitymeasurements.

Another modification of the Victor Meyer apparatus employs a centralvaporization tube which extends downwardly into and almost to the bottomof the inner jacketed compartment of the vaporizer. The sample bulb isfastened at the top of this central tube so that when crushed the vapormust pass downward through the central tube and then upward around it tothe top before reaching the unjacketed part of the apparatus. While thisapparatus is conveniently and simply constructed it is possible forvapor to escape therefrom with the air to Vitiate the measurements ofvapor density.

It is therefore the object of the present invention to provide amodification of the Victor Meyer vapor density measuring apparatus whichis almost completely free from the danger of vapor condensation andescape; which is compact; which is durable; and which is convenient andeasy to use.

Other and further objects of the present invention will appear from thefollowing description of an illustrative embodiment thereof.

The vapor density measuring apparatus of the present concept is capableof various mechanical embodiments one of which is shown in theaccompanying drawing and is described hereinafter to illustrate theinvention. This illustrative embodiment of the present invention shouldin no way be construed as defining or limiting the same.

In the accompanying drawings, in which like reference charactersindicate like parts, FIG. 1 is an elevational view of an illustrativeembodiment of the present concept showing the vaporization chambersurrounded by a spaced outer jacket with the exit tube from thevaporization chamber coiled around the outside of the vaporizationchamber and within the outer jacket;

FIG. 2 is a detail of a portion of the embodiment of FIG. 1 on the lines22 thereof;

FIG. 3 is an elevational view of the device employed with the embodimentof FIG. 1 for breaking the sample bulb and for reducing turbulence andconvection currents in the vaporization chamber; and

FIG. 4 is a view of the assembled embodiment of FIGS. 1 and 3 mounted ona stand and ready for use.

Referring now to the several figures, 10 is an outer jacket of elongatedcylindrical form of suitable material such as Pyrex glass having outlet11 formed at the top thereof for connection to any suitable condenser,not shown, and provided with a mouth 12. A vaporizing chamber 13, alsoof Pyrex glass, is sealed within jacket 10 beneath mouth 12 along sealline 14. Chamber 13 is spaced from and extends within jacket 10 and hasbottom 15 spaced from and adjacent to bottom 16 of jacket 10. Exit tube17 opens into the upper end of chamber 13 and is sealed to the wallthereof at 18. Tube 17 is wound downwardly around the outside of chamber13; is formed in a turn at 19; and then is wound upwardly around theoutside of chamber 13 in the helical space between the downward turnsthereof. Tube 17 passes out through the upper portion of jacket 10 at 20and is sealed thereto to form a vapor tight seal. Exits tube 17terminates in an end portion 21 for connection to a suitable measuringburet, not shown.

The device for breaking the bulb containing the sample to be vaporizedis seen in FIG. 3. This breaking device includes a glass tube 22 whichis of sufficient length to extend to adjacent the bottom of vaporizingchamber 13, as seen in FIG. 4. Tube 22 passes through a cork or seal 23which forms a vapor tight fit in mouth 12. A wire 24 is secured adjacentthe upper end of tube 22 and within tube 22, as at 25, and the upper endof tube 22 is suitably sealed against the escape of vapor by anysuitable seal here shown as a length of rubber tubing 26 embracing tube22 and closed by a length of glass rod 27 mounted therein. A sample bulb28 is hooked to or suitably secured to the lower end of wire 24 as at29. A plurality of spaced perforated discs 30 are mounted on tube 22 andform a loose fit in vaporizing chamber 13 to prevent turbulence of vaporflow and convection currents in vaporizing chamber 13.

When in use, the apparatus of the present concept is method as shown inFIG. 4 on a stand 31 having an upwardly extending support 32 which isprovided with a clamp 33 carrying a suitable heat diffusing element 34.Any suitable source of heat such as a Bunsen burner, not shown, issupported on stand 31 beneath element 34. Upright 32 carries a secondclamp 35 which supports jacket 10 between forks 36. When the apparatusis to be used a suitable heat conducting liquid is placed in jacket 10the steam or vapor from which heats vaporizing chamber 13. If the heatconducting liquid is volatile mouth 11 is connected to a suitablecondenser, not shown,

and the conducting liquid is heated. The material to be tested is thenplaced in sample bulb 28 which is then sealed, Weighed and connected towire 24. Tube 22 is inserted into vaporizing chamber 13 with seal 23making a vapor tight fit with mouth 12. Bulb 28 is then crushed bymanipulation of wire 24 at the flexible joint 25 and the sample isvaporized in chamber 13 with the vapors passing outwardly therefrom andinto the tube 17. Displaced air passing out of tube 17 through extension21 thereof is then led to any suitable measuring buret, not shown, andvapor density measurements are completed in wellknown manner.

Because of the great length of exit tube 17 compared to the length ofvaporizing chamber 13, the air displaced by the vaporization of thesample can be readily measured Without loss of vapor from the apparatusand without condensation of vapor. Exact and accurate measurements ofvapor density of the sample can therefore be obtained. In arepresentative embodiment of this apparatus jacket 10 may have anoverall height of 31 cm.; an outside diameter of cm.; and exit tube 17may have an inside diameter of 6 cm. and an over-all length of 2 111. (6/2 feet).

Typical student results are given in Table 1. Routine vapor densitydeterminations by students using the apparatus of the present inventionas described above have been less subject to erratic errors than withprior known forms of the apparatus:

TABLE 1 Illustrative Student Data, Using Ethylaniline (B.P. 204) asBoiling Liquid Substance Benzene (78.11)

It should now be apparent to one skilled in the art that the vapordensity measuring apparatus of the present invention in every waysatisfies the several objectives described above.

Changes in or modifications to the above-described illustrativeembodiment of this invention may now be suggested to those skilled inthe art without departing from the present inventive concept. Referenceshould therefore be had to the appended claims to determine the scope ofthis invention.

What is claimed is:

1. In a vapor density measuring apparatus, a jacket, a mouth in saidjacket, a vaporizing chamber in said jacket communicating with saidmonth, an exit tube sealed to and opening into said chamber adjacentsaid mouth and wrapped downwardly around and then upwardly around theoutside of and extending substantially the length of said chamber Withinsaid jacket, said exit tube being sealed to and passing outwardlythrough said jacket adjacent said mouth and means for introducing asample to be tested into said chamber said means closing said mouth witha vapor tight seal.

2. Apparatus as described in claim 1, said jacket being an elongatedhollow cylinder closed at one end with said mouth at its opposite end,said chamber being an elon gated hollow cylinder closed at one endadjacent to and spaced from the closed end of said jacket and sealed atits other end to said jacket adjacent said mouth.

3. Apparatus as described in claim 2 in which said means comprises ahollow tube, a wire extending through said tube, a stopper on said tubeadjacent an end thereof for sealing said mouth, means for closing saidtube adjacent said stopper and a sample bulb carried by said wire at theend of said tube away from said stopper.

4. Apparatus as described in claim 3 including spaced perforated discsmounted on said tube and forming a loose fit in said chamber. I

5. Apparatus as described in claim 1 including means for introducing aheating liquid into said jacket around said chamber and around saidtube.

References Cited in the file of this patent UNITED STATES PATENTS1,034,170 Vanier a July 30, 1912

1.IN A VAPOR DENSITY MEASURING APPARATUS, A JACKET, A MOUTH IN SAIDJACKET, A VAPORIZING CHAMBER IN SAID JACKET COMMUNICATING WITH SAIDMOUTH, AN EXIT TUBE SEALED TO AND OPENING INTO SAID CHAMBER ADJACENTSAID MOUTH AND WRAPPED DOWNWARDLY AROUND AND THEN UPWARDLY AROUND THEOUTSIDE OF AND EXTENDING SUBSTANTIALLY THE LENGTH OF SAID CHAMBER WITHINSAID JACKET, SAID EXIT TUBE BEING SEALED TO AND PASSING OUTWARDLYTHROUGH SAID JACKET ADJACENT SAID MOUTH AND MEANS FOR INTRODUCING ASAMPLE TO BE TESTED INTO SAID CHAMBER SAID MEANS CLOSING SAID MOUTH WITHA VAPOR TIGHT SEAL.